Commonly owned, patent application Ser. No. 09/750,572, filed on Dec. 28, 2000, entitled xe2x80x9cFAST ACTING, ELECTRICALLY POWERED OPERATOR FOR TRANSFER SWITCH AND TRANSFER SWITCH INCORPORATING SAMExe2x80x9d.
1. Field of the Invention
This invention relates to switches for electric power distribution systems and, more particularly, to electrically powered operators for interlocking the operation of a pair of switches, such as those in a transfer switch.
2. Background Information
Transfer switches commonly used to connect alternate power sources to a load, including networks, utilize a pair of switches each connecting one of the sources to the load. In order to prevent connecting unsynchronized sources together, the operation of the two switches is coordinated, typically by a mechanical interlock, so that only one switch at a time can be turned ON. In many instances, it is desirable to operate the transfer switch remotely. Typically, electric motors have been used to operate the interlocks on transfer switches. The motor powered interlocks operate relatively slowly so that there is a noticeable dead period between the time that one of the switches is turned OFF and the other is turned ON. It is desirable to minimize this dead period while assuring that the two switches are never both ON at the same time.
U.S. Pat. No. 4,553,115 describes a solenoid powered operator for a single, molded case circuit breaker. This device operates the circuit breaker handle rapidly each time the solenoid is energized. It would be desirable to be able to operate the pair of switches in a transfer switch at a similar rapid rate, thereby reducing the interval in which the load is unenergized.
There is a need, therefore, for an improved operator for the switches of a transfer switch which allows the transfer to be made more rapidly.
This need, and others, are satisfied by the invention which is directed to a fast acting, electrically powered operator for first and second electric power switches mounted in spaced confronting relation with the handles facing each other and reciprocal together to oppositely switch the associated electric power switches on and off. The electrically powered operator comprises a solenoid and a mechanical assembly coupling the solenoid to the first handle and the second handle to reciprocate them to simultaneously turn one of the electric power switches on and the other off, and then to turn the one off and the other on, on successive actuations of the solenoid.
The solenoid is a single action solenoid having an electromagnet and an armature moveable relative to the electromagnet. The mechanical assembly comprises first and second electromagnet drive members secured to the electromagnet and extending toward the first handle and second handle, respectively. First and second armature drive members are secured to the armature and extend toward the first and second handle, respectively. The mechanical assembly also includes a latch mechanism reciprocal between a first latch position in which the first and second electromagnet drive members are held fixed and the first and second armature drive members move upon actuation of the single action solenoid, and a second latch position in which the first and second armature drive members are held fixed and the first and second electromagnet drive members move upon actuation of the single action solenoid. The first electric power switch is turned on and off on successive actuations of the single action solenoid by reciprocation of the first handle through alternate movement of the first handle by one and then the other of the first electromagnet drive member and the first armature drive member. The second electric power switch is turned on and off oppositely to the first electric power switch on successive actuations of the single action solenoid by reciprocation of the second handle through alternate movement of the second handle by one, and then the other, of the second electromagnet drive member and the second armature drive member. A handle yoke which also forms part of the mechanical assembly engages one of the handles and switches the latch mechanism between the first and second latch positions as that one handle reciprocates.
The invention also embraces a transfer switch incorporating first and second electric power switches with associated handles rectilinear reciprocal to turn the associated switch off and on, a mount mounting the first and second electric power switches in spaced relation with the handles confronting one another and the electrically powered operator as described.